1. Field of the Invention
The present invention relates to a take-out apparatus to take out a sheet one by one separated from sheets in the stacked state.
2. Description of the Related Art
So far, for example, a postal matter take-out apparatus (hereinafter, simply referred to as a take-out apparatus) to take out one by one from postal matters in the stacked state and feed to a processing portion at the latter stage is known as a take-out apparatus.
This take-out apparatus has a stacker to house plural postal matters in the stacked state in the erected position. There is a take-out roller provided to pressure push postal matters out of plural postal matters stacked in the stacker at one end in the stacked direction. This apparatus has a separation portion to receive the postal matters taken out by the take-out roller and pass through a nip portion formed between a feed roller and separate postal matters taken out in the overlapped state. Further, the apparatus has a pull out portion to receive the front end of a postal matter passing through the nip portion of the separation portion and pulling it out and feed to the processing portion at the latter stage.
The take-out roller rotates in a prescribed direction and takes out postal matters at one end in the stacked direction on a conveying path. The take-out roller is arranged to press fit to postal matters at one end in the stacking direction using a spring/a counter balance.
The separation portion has a feed roller to feed postal matters taken out by the take-out roller on the conveying path along it and a separation roller in contact with the feed roller on the conveying path. The separation roller generates a torque in the direction reverse to the conveying direction and separates a second and subsequent postal matters from postal matters at one end of the stacking direction.
The pull out portion has a pull out roller pair that rotates at a peripheral velocity faster than at least the feed roller of the separation portion, and pulls out a postal matter clamped in the nip portion between the feed roller and the separation roller of the separation portion. Thus, the velocity of the feed roller of the separation portion and that of the pull out roller are differentiated, a gap between postal matters being conveyed on the conveying path is kept at a constant level.
However, in a conventional take-out apparatus described above, the take-out roller is pressed against postal matters at one end in the stacking direction using a spring or a counterbalance and therefore, a contact pressure of the take-out roller to postal matters at one end in the stack direction changes depending on difference in volume, elasticity, weight, etc. of postal matters stacked at one end of the stacking direction and the contact pressure could not be stabilized. Therefore, in the case of conventional apparatus, all of stacked postal matters could not take out under the same conditions and various problems were taken place. That is, there were such problems that if the contact pressure of the take-out roller was lower than a proper value, postal matters could not taken out and if the contact pressure was higher than a proper value, two sheets were taken out at a time in many cases.
Further, in the case of the above-mentioned conventional taken out apparatus, postal matters thicker or thinner than a defined thickness were processed jointly with postal matters in defined thickness and such postal matters in different materials as paper, vinyl sheets, etc. Therefore, the separation torque in the separation portion was set at a relatively large torque. That is, in order to separate all postal matters in different state one by one in the separation portion, it was necessary to increase the separation efficiency by setting a torque in the reverse direction by the separation roller relatively large. However, when the torque of the separation roller is increased, there was such a problem that postal matters were contaminated or damaged by a friction between the surfaces of postal matters and the separation roller when postal matters are pulled out by the pull out pair.
Furthermore, in the case of the above-mentioned conventional take-out apparatus, plural postal matters are taken out by the take out roller and the velocity of the feed roller of the separation portion and the pull out roller is made difference so as to form a certain gap between postal matters. However, there were many cases wherein a gap could not stabilize by jamming or slip of postal matters.